Find all School-related info fast with the new School-Specific MBA Forum

It is currently 18 Dec 2014, 12:12

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

M16#8

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Forum Moderator
Forum Moderator
User avatar
Status: waiting for good news
Joined: 02 Jul 2009
Posts: 1263
GPA: 3.77
Followers: 161

Kudos [?]: 549 [0], given: 540

GMAT ToolKit User Premium Member Reviews Badge
Re: M16#8 [#permalink] New post 12 Nov 2010, 12:05
hi guys

My respect to that person who created this question.

Here is very nice questions, which shows how tricky may be GMAT questions. Professionals who create such questions are also phycometrists - (or smth like that). They are sycologists who know how the logical flow of an ordinary person works and what are the gaps.
Most of you have realised that in 1) In the first 2 hours the bus.... - they talk about a part of total time
in 2) The average speed of the bus for the first half of the distance was - they talk about a part of total distance.

you want to solve it rapidly you have heard about half of and your brain does not want to care about this anymore.

This question may pretend to become one of my favorite questions.
_________________

Follow me, if you find my explanations useful.

Audaces fortuna juvat!

Kaplan Promo CodeKnewton GMAT Discount CodesManhattan GMAT Discount Codes
Intern
Intern
avatar
Joined: 18 Jan 2010
Posts: 4
Schools: Kellogg
Followers: 0

Kudos [?]: 0 [0], given: 0

GMAT ToolKit User
Re: M16#8 [#permalink] New post 02 Feb 2011, 12:01
It took the bus 4 hours to get from town A to town B. What was the average speed of the bus for the trip?

1. In the first 2 hours the bus covered 100 miles
2. The average speed of the bus for the first half of the distance was twice its speed for the second half

Statement 1: This tells me that during the first 2 hours, the speed of the bus is 50mph.

Statement 2: This is not sufficient because I do not know the average speed of the bus during the first half of the distance or the second half of the distance.

Statement 3: We should NOT assume that during the first 2 hours of the trip, the bus has covered the first half of the distance. We do not know the total distance of the trip. Both statements will not give us the answer.

My answer is E. Very tricky C-trap question.
Current Student
User avatar
Joined: 16 Sep 2010
Posts: 227
Location: United States
Concentration: Finance, Real Estate
GMAT 1: 740 Q48 V42
Followers: 7

Kudos [?]: 64 [0], given: 2

Re: M16#8 [#permalink] New post 14 Feb 2011, 21:11
E. No where in the question does it state the total distance. You can be fooled into thinking C by assuming that 100 miles is half the distance. However it never states this.
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 24589
Followers: 3802

Kudos [?]: 32780 [0], given: 3558

Re: M16#8 [#permalink] New post 04 Feb 2012, 05:59
Expert's post
This question is also discussed here: if-it-took-a-bus-4-hours-to-get-from-town-a-to-town-b-what-102361.html

There is a following trick in the question:

If (2) were: The constant speed of the bus for the first half of the distance was twice its constant speed for the second half.

Then for (1)+(2) we would have: s_1*\frac{4}{3}+\frac{s_1}{2}*(2-\frac{4}{3})=100 --> we can find s_1 so we can find d (d=2*s_1*\frac{4}{3}).

BUT: as it is now, we don't know whether the average speed after first \frac{4}{3} hours till 2 hours from the start was \frac{s_1}{2} or less or more, we just know that the average speed from first \frac{4}{3} hours till 4 hours from the start was \frac{s_1}{2}.

Hence the answer is E.

Hope it's clear.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Manager
Manager
avatar
Status: MBA Aspirant
Joined: 12 Jun 2010
Posts: 178
Location: India
Concentration: Finance, International Business
WE: Information Technology (Investment Banking)
Followers: 3

Kudos [?]: 29 [0], given: 1

Re: M16#8 [#permalink] New post 06 Feb 2012, 02:53
The answer is E.
For solving this question we ought to know the distance between the towns A & B. Since none of the statements provide that so the answer is E.
Manager
Manager
avatar
Joined: 10 Jan 2011
Posts: 244
Location: India
GMAT Date: 07-16-2012
GPA: 3.4
WE: Consulting (Consulting)
Followers: 0

Kudos [?]: 23 [0], given: 25

Reviews Badge
Re: M16#8 [#permalink] New post 08 Feb 2013, 02:56
Lets assume total distance = 2d.

we need to calculate 2d/4 = average speed for entire trip.

statement 1: tells us that bus travel 50MPH for first 2 hrs... clearly not sufficient.

statement 2: let 2v be the speed for first half, then v be the speed for second half.
d/2v + d/v = 4
d/4 = 2vsqure/3v
d/4 = 2/3 v.
as we don't know v. statement 2 is not sufficient.

combining st1 and 2. we can not calculate v. as 50 MPH given for first 2 hr and not first half of the journey.

Answer is E.
_________________

-------Analyze why option A in SC wrong-------

Intern
Intern
avatar
Joined: 06 May 2013
Posts: 6
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: M16#8 [#permalink] New post 22 Jan 2014, 13:03
OA should be E.
There is no way we can calculate the Average speed.
From 1) we cannot say that 100 miles is half a distance. It might possible that 100 miles is only the one third of the distance and bus covers rest 2/3 distance in another 2 hrs. Making total of 4 hrs of total journey.
From 2) only gives the ratio of speeds for the first half to the second half.

Even using both these we cannot find the average speed.
Manager
Manager
avatar
Joined: 20 Oct 2013
Posts: 77
Followers: 0

Kudos [?]: 7 [0], given: 13

GMAT ToolKit User Premium Member
Re: M16#8 [#permalink] New post 20 Apr 2014, 07:45
1) No relation is drawn between the trip A-B and 100 miles -> insufficient
2) We need a specific figure for the ans -> also insufficient
Combine 2 stats:
From 2), the time spent on the first half of the trip is 1/2 that spent on the 2nd half => time spent on 1st half = 4/3hrs
-> from 1): 2a*4/3+a*2/3=100 -> a=30 -> average speed on the trip = [60*4/3+30*8/3]/4=40

Choose C
Re: M16#8   [#permalink] 20 Apr 2014, 07:45
Display posts from previous: Sort by

M16#8

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page   Previous    1   2   [ 28 posts ] 

Moderators: Bunuel, WoundedTiger



GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.